DE102012217890B4 - Combination of pressure charging and metering for continuous delivery of fuel dust into an entrainment gasification reactor over long distances - Google Patents

Abstract

System for pneumatic fuel dust feed on the principle of flow promotion in an entrained flow gasification reactor (7), in particular by overcoming conveyor lines of 80 to 500 m, in the by reaction with oxygen or a free oxygen-containing gasification agent at pressures between 1 and 10 MPa and temperatures between 1300 and 1600 ° C, a raw gas rich in H2 and CO, wherein - a raw fuel stocked in a raw fuel silo (2) is fed to a device (3) for drying and grinding to form combustible dust, - the fuel dust is subsequently removed in the filter (4) from entrained dryer and circulating gas is released, - set in a combined Staubschleusungs- and metering vessel (5) the fuel under operating pressure and introduced in the fluidized state in the defined stream in a dust delivery line (6), - the fuel in the fluidized state by flow promotion through the Dust delivery line (14) the Flugstromv gasification reactor (7) is supplied, - a plurality of combined Staubschleusungs- and Dosiergefäße (5) are arranged, the discontinuously (cyclically) filled with fuel dust and pressurized their contents the entrained flow gasification reactor (7) continuously supplied by the filling and Bespannungsvorgang the Setpoint for the fuel dust mass flow control on the control valves (11) of the dust conveying lines (6) of the first and second Staubschleusungs- and Dosiergefäßes (5) is divided, wherein via a share divider (18), a displacement of the setpoint from the first to the second control valve (11) and the displacement of the setpoint takes place via a ramp whose time t1 is adjustable and the output of the ramp is multiplied by the mass flow setpoint for the second control valve (11) and for the first control valve the output of the ramp is subtracted from 1 and multiplied by the mass flow setpoint is parallel to the control of the Control valves (11) the supply of fluidizing gas (16) under the fluidized beds (15) started and the promotion is received.

Description

The invention relates to a system for fluidizing and conveying a dust-like material, in particular fuel dust, under an operating pressure of up to 10 MPa to a receiver, in particular entrained flow gasification device.

The invention also relates to a process for continuous feeding of pulverized fuel into an entrained-flow gasification plant at pressures of up to 10 MPa for producing a CO- and H2-rich crude gas which can be processed to various synthesis gases, energetic gases and hydrogen.

The feeding of the fuel dust into the standing under a pressure of up to 10 MPa gasification system is done either by pumping a fuel dust-water slurry, fuel dust oil slurry or a Brennstaub carrier gas suspension with delivery densities of 250-450 kg / m3 in the flow promoter. A detailed description of this technology is contained in the patent DD 147188 A3 , Thereafter, the fuel dust produced in a grinding and drying plant is fed via a conventional Dünnstromförderung an operating bunker and the conveying gas separated via a filter. To increase the pressure of the fuel dust passes through gravity in pressure locks, in which the dust is brought by stringing with an inert gas having less than 5% oxygen to the desired process pressure. As inert gases nitrogen, carbon dioxide or exhaust gases from the combustion can be used. Depending on the performance, the pressure locks can be executed once or several times. From the pressure locks the fuel dust passes again by gravity in a dosing, in the lower part of a device for generating a dense fluidized bed is arranged, immerse in the one or more delivery lines for transporting the fuel dust to the burner of the gasification reactor. By applying and possibly regulating a predetermined pressure difference between the dosing and the gasification reactor, the desired amount of fuel dust can be supplied. Together with the amount of oxygen adapted to the amount of fuel dust, the conversion takes place at such temperatures in the gasification reactor that the fuel ash is melted down into liquid slag. This arrangement has several disadvantages. The amount of fuel to be supplied from a grinding and drying plant over a long distance to the operating bunker of the gasification plant in the thin stream requires a very large conveying gas requirement, which must be provided continuously. The arrangement of an operating bunker comprising several thousand tons of fuel dust as well as the locks and the metering vessel in the area of the hot gasification reactor can lead to heavy fires in the event of leaks or accidents, which can lead to destruction of the entire plant. To avoid these disadvantages has been disclosed in the publications DE 102008052673 as well as in DE 102009035408 proposed to arrange the bunker and lock system in the field of grinding and drying plant and set up only a dosing in the hot gasification reactor. To overcome the longer transport route, dense phase conveying should also be used here. The disadvantage here is the serial arrangement of two Dosiergefäße. The pulverized coal to be pulverized is fed via a filter, as usual, to an operating bunker and placed in one or more locks under process pressure. By gravity feed the fuel dust passes into a first metering vessel, from which it is fed in dense stream a second metering, which is located in the immediate vicinity of the gasification reactor. The fuel dust is separated from the conveying gas, so that builds up a bed. In the lower part is in turn a device that allows a supply of one or more dust delivery lines that supply the fuel dust in the dense stream to a central gasification burner or more arranged gasification burners of the gasification reactor. The advantage here is the saving of conveying gas by applying the dense stream technology and the local separation of dust-carrying large container from the hot gasification reactor, disadvantageous is the multiple execution of the dosing. Furthermore, there is a risk that at a greater distance between the two dosing due to the pressure loss and the associated expansion of the conveying gas, the transport speed of the gas-dust suspension is so high that wear in the delivery lines can occur. The danger increases, the lower the pressure level is.

From the DE 102009048931 A1 is a Dichtstromförderanlage with dosing for the continuous, continuous and metered supply of fuel dust in including entrained flow gasification reactors in which the continuous, continuous, metered feeding is provided by a coupled, coordinated operation of the two or more dosing of the dosing by the individual dosing, if they are empty, be subjected to a negative pressure relative to the supply device for filling with bulk material from the supply device and be acted upon at a fill level maximum with stringing gas to an operating pressure. Now reaches a metered dosing, from which the dust is fed into the delivery pipes, a level minimum, ie just before it runs empty, so causes the coupled, level-controlled, coordinated operation of the dosing the sliding attachment of a second Dosing, which is filled to a maximum fill level with bulk material is pressurized by the emptying first dosing is connected via the pressure equalization line with the second full dosing, while the dust flow control devices of the first dosing stop the conveying into the delivery pipes, and at the same time opening the dust flow control devices the second dosing container takes place in a coordinated manner by the control device. Thus, when signaling the minimum level of the metering container by the control device, the pressure equalization line is opened to a full, pressurized to operating pressure metering, and closed the respective dust flow control devices closed or opened at prevailing pressure equalization of both metering, so that the mass flow in the respective delivery pipes remains constant. This sliding change of the dosing preferably runs automatically level, pressure and mass flow controlled without the dust supply is interrupted or occurs irregularly.

In this known dosing, in which a pressure equalization between two dosing containers to be switched takes place, the dust flow, taking into account different pipe lengths and characteristics only be kept constant, that promotes according to the teaching taught only one of the dosing to the consumer. This is accomplished according to the teaching taught by the fact that after pressure equalization open the dust flow control units of the filled dosing immediately, at the same time close the dust flow control units of the empty dosing but in slow synchronous mode.

The invention has for its object to provide a system for pneumatic Brennstaubzuführung in an operated at an operating pressure up to 10 MPa Flugstromvergaser in which alternately a plurality of metering vessels continuous quantitative dust flow is given to the Flugstromvergaser without a pressure equalization between the Dosiergefäßen is required.

The object is achieved by a system having the features of the first claim.

The inventive system eliminates the burden of pressure equalization lines between the dosing and their control and the cost of a quick closing or slow opening of the dust flow control units.

In the context of the invention, the fuel dust, which comes from the grinding and drying plant, separated in a filter from the drying and recycle gas and fed to a dosing, in which the pressurization and the dosage are combined in the transport line to the entrained flow gasification plant. These are at least two or more pressure locks 5 arranged, each discontinuously by gravity from the said filter 4 be fed and start pumping after pressurization. For this purpose, according to the prior art incorporated in the lower part of the fluidized beds above which builds up by supplying fluidizing gas, a fluidized bed in which the dust delivery line 6 it starts. The dust transfer and dosing vessels 5 are operated alternately with regard to the application of operating pressure. In this case, always at least one metering vessel is filled and subsequently covered and another under operating pressure of z. B. 4.7 MPa and fluidized the fuel dust in the fluidized shaft. From this Schleusungs- and metering of the fuel dust, especially coal dust, is continuously fed into the gasification reactor. The control of the amount is thereby arranged by a arranged at the outlet of the metering control valve 11 causes. The dust delivery lines of several lock and metering vessels are after the control valves to a common delivery line 14 but can also be used in long conveying sections on several split conveying lines ( 14a . 14b . 14c ) be further divided. To ensure continuous operation, it is switched to a second vessel before emptying the lock and metering vessel in operation. This is done after its filling and stringing process is completed. The setpoint 9 . 21 for the coal mass flow control is subsequently divided on the control valve of the first and second metering vessel, wherein via a so-called share divider, a displacement of the desired value from the first to the second valve. The shift of the setpoint takes place via a ramp whose time (t1) can be set, as in 3 shown.

The output of the ramp is multiplied by the mass flow setpoint for the second valve, and for the first valve, the output of the ramp is subtracted from 1 and then multiplied by the mass flow setpoint. In this way, a constant promotion in the gasification reactor can be ensured during the switching / crossfading. Parallel to the control of the arranged under the lock and dosing vessel Brennstaubregelarmaturen ( 11 ), the supply of fluidizing gas ( 17 ) into the lower part of the fluidized beds. Ideally, this takes place before the start of coal mining, in order to achieve a stable fluidized bed.

By switching / blending the setpoint and the individual control of each Schleusungs- and Dosiergefäßes no limitation of coal extraction is necessary. The for the dense phase flow possible flow velocities of 2 to 8 m / s are maintained throughout the course of the dust delivery line.

Due to the mutual connection of several of these Schleusungs- and Dosiergefäße despite the discontinuity in the operation of the pressure vessels, a continuous supply of the fuel to the gasification reactor can be secured.

The invention leads to a considerable reduction in expenditure and the possibility of installing the lock and metering vessels far away from the gasification reactor in order to increase the safety in the environment of the hot gasification reactor.

Advantageous developments of the invention are specified in the subclaims.

The invention is explained in more detail below as an exemplary embodiment in a scope necessary for understanding with reference to figures. Showing:

1 the interaction according to the invention of essential elements of a coal grinding and drying plant with the gasification plant,

2 a special solution for large conveyor lengths and

3 the blending from one metering vessel to another metering vessel in a time interval t0 to t1.

In the figures, like names denote like elements.

Example 1:

A gasification plant after 1 for the production of synthesis gas has a capacity of 500 MW gross. The demand for fuel dust is 82 mg / h. In addition, the raw coal is transported via crude coal conveying technology 1 a raw coal silo 2 abandoned and in the two-line drying and grinding plant 3 to a fuel dust with a residual water content of 2.5 Ma% and a grain size of 50 Ma% less than 60 microns processed. This fuel dust is in the dust filter 4 separated from drying and recycle gas. The dust temperature is 50 ° C. There are a total of three combined pressure and metering locks 5 available (only two drawn), the reciprocal gravity extraction from the dust filters 4 be fed and covered by supplying oxygen-free or oxygen-poor gas. This allows, despite the discontinuous filling and Bespannungsvorganges the combined dust lock and Dosiergefäße a continuous dust supply from the dust conveyor lines 6 and the line 14 to the gasification reactor 7 to reach. The clothing pressure in the pressure and metering locks 5 corresponds to the pressure in the entrained flow gasification reactor 7 plus the pressure loss in the dust conveyor lines 6 and 14 , The stringing gases can be given by nitrogen, carbon dioxide, low-oxygen exhaust gases but also combustible gases such as natural gas or residual gases from the overall process. The covering of the combined dust lock and dosing vessel 5 For example, with the fluidizing gas 16 done that, under the fluidized floor 15 is supplied. The fuel dust is already above the fluidized bed 15 loosened. Once the desired operating pressure has been reached, it can be opened by opening the valve 11 the promotion of the fuel dust and by the quantity measurement 9 that the control valve 11 controls, and optionally by additional gas 8th in the dust conveyor line 14 the desired amount of fuel can be adjusted. The fuel dust is transferred via the dust conveyor 14 the gasification reactor 7 fed, in which the sales of the gasification agents oxygen and optionally water vapor, but also carbon dioxide to gasification gas takes place. The gasification gas is passed over the line 12 corresponding equipment / facilities supplied for further treatment. The dust conveyor lines 6 and 14 can have dimensions between 10 and 100 mm. The distance between the combined dust transfer and metering vessel 5 and the gasification reactor 7 is 200 meters.

When the desired dust supply, there is a pressure drop between the vessel 5 and the entrained flow gasification reactor 7 of 0.7 MPa at a total pressure of the plant of 4.7 MPa. This corresponds to approx. 15% of the total pressure. This value can be up to 20%.

In order to ensure continuous operation, before complete emptying of the lock and metering vessel in operation 5 on a second lock and Dosiergefäß 5 switched without the continuity of the dust flow in line 14 is disturbed. This takes place after the filling and stringing operation of the second lock and Dosiergefäßes 5 is completed. The setpoint for the coal mass flow control of 82 mg / h will follow the control valves 11 the first and second lock and Dosiergefäßes 5 split, with the share divider 18 makes the setpoint from the first to the second valve. The shift of the setpoint takes place via a ramp whose time t1 can be set. The output of the ramp is at the mass flow set point for the second control valve 11 multiplied and for the first control valve 11 the output of the ramp is subtracted from 1 and multiplied by the mass flow setpoint. In this way, a steady promotion in the gasification reactor 7 during conversion to the other lock and dosing vessel 5 be ensured. A further influence on the dust flow control, in particular also fine control, by the in the fluid gas line 16 located control valves 17 or the supply of additional gas 8th into the auxiliary gas feed 13 the dust conveyor line 14 be made.

Example 2:

A gasification plant after 2 , simplified and without 11 . 17 . 18 shown, offers the same capacity as in Example 1. The distance between the combined dust lock and Dosiergefäßen 5 and the entrained flow gasification reactor 7 is about 500 m. To the pressure loss in the dust delivery lines 6 and 14 to limit and also to keep the flow rate below 8.5 m / s, is in the dust delivery line 14 after a distance of 250 m a dust flow divider 19 used, the dust flow evenly on the three dust conveyor lines 14a , b, c divides. The three dust conveyor lines 14a , b, c may be connected to the three fuel-dust feeders of a high-performance burner or each to the fuel-dust feed of one of three burners. The further procedure corresponds to example 1.

In the dust lock and Dosiergefäßen 5 common dust conveyor line 14 Can be a flow meter and regulator for the entire dust flow 21 be arranged. In accordance with the in the quantity measurement and controller for the entire dust flow 21 determined quantity flow is the dust lock and Dosiergefäßen 5 total inflowing amount of fluidizing gas via a control valve for the total amount of fluidizing gas 22 in the fluid gas line 16 controllable in the sense of a higher-level control.

Example 3:

An entrained-flow gasification plant with an output of 500 MW also receives 82 mg / h of combustible dust over a distance of 500 m in three combined dust lock and dosing vessels 5 put under pressure and into the dust conveyor lines 14 is fed. The diameters of the delivery lines are 0.06 m. In order to limit the pressure loss in the dust conveying lines and the flow velocity of the gas and pulverized fuel suspension, their cross sections are doubled after a conveying distance of 250 m, so that their diameters increase to 0.085 m.

• – ein in einem Rohbrennstoffsilo 2 bevorrateter Rohbrennstoff einer Einrichtung 3 zum Trocknen und Mahlen zu staubförmigem Brennstoff zugeführt wird,
• – der Brennstaub anschließend im Filter 4 vom mitgeführten Trockner- und Kreislaufgas befreit wird,
• – in einem kombinierten Staubschleusungs- und Dosiergefäß 5 der Brennstaub unter Betriebsdruck gesetzt und im fluidisierten Zustand im definierten Strom in eine Staubförderleitung 14 eingeführt wird,
• – der Brennstaub im fluidisierten Zustand mittels Fließförderung durch die Staubförderleitung 14 dem Flugstromvergasungsreaktor 7 zugeführt wird,
• – mehrere kombinierte Staubschleusungs- und Dosiergefäße 5 angeordnet sind, die diskontinuierlich (zyklisch) mit Brennstaub gefüllt und unter Druck gesetzt ihren Inhalt dem Flugstromvergasungsreaktor 7 kontinuierlich zuführen, indem nach dem Befüllungs- und Bespannungsvorgang der Sollwert für die Brennstaubmassenstromregelung auf die Regelventile 11 der Staubförderleitungen 6 des ersten und zweiten Staubschleusungs- und Dosiergefäßes 5 aufgeteilt wird, wobei über einen Anteilsteiler 18 ein Verschieben des Sollwertes vom ersten auf das zweite Regelventil 11 erfolgt und die Verschiebung des Sollwertes dabei über eine Rampe erfolgt, deren Zeit t1 einstellbar ist und der Ausgang der Rampe mit dem Massenstromsollwert für das zweite Regelventil 11 multipliziert wird und für das erste Regelventil der Ausgang der Rampe von 1 subtrahiert und mit dem Massenstromsollwert multipliziert wird, wobei parallel zu der Ansteuerung der Regelventile 11 die Zuführung von Wirbelgas 16 unter die Wirbelböden 15 gestartet und die Förderung aufgenommen wird.

The invention is also provided by a system for pneumatic Brennstaubeinspeisung according to the principle of flow promotion in an entrained flow gasification reactor 7 , in particular by overcoming conveyor lines of 80 to 500 m, in which a hydrogen gas rich in H 2 and CO is produced at temperatures of between 1 and 10 MPa and temperatures between 1,300 and 1,600 ° C by reacting with oxygen or a free oxygen-containing gasification agent, in which

• - one in a raw fuel silo 2 stockpiled raw fuel of a facility 3 for drying and grinding is fed to pulverulent fuel,
• - The fuel dust then in the filter 4 is freed from entrained dryer and recycle gas,
• - In a combined Staubschleusungs- and Dosiergefäß 5 the fuel dust is set under operating pressure and in the fluidized state in the defined stream in a dust delivery line 14 is introduced
• - The fuel dust in the fluidized state by flow promotion through the dust delivery line 14 the entrained flow gasification reactor 7 is fed
• - Several combined Staubschleusungs- and Dosiergefäße 5 arranged discontinuously (cyclically) filled with fuel dust and pressurized their contents the entrained flow gasification reactor 7 continuously feed, by after the filling and Bespannungsvorgang the setpoint for the Brennstaubmassenstromregelung on the control valves 11 the dust conveyor lines 6 the first and second Staubschleusungs- and Dosiergefäßes 5 is split, using a share divider 18 a shifting of the setpoint from the first to the second control valve 11 takes place and the displacement of the setpoint takes place via a ramp whose time t1 is adjustable and the output of the ramp with the mass flow setpoint for the second control valve 11 is multiplied and subtracted for the first control valve, the output of the ramp of 1 and multiplied by the mass flow setpoint, wherein in parallel to the control of the control valves 11 the supply of fluidizing gas 16 under the fluidized floors 15 started and the support is received.

Claims (12)

System for pneumatic pulverized fuel injection according to the principle of flow promotion in an entrainment gasification reactor ( 7 ), in particular by overcoming conveyor lines of 80 to 500 m, in which by reacting with oxygen or a free oxygen-containing gasification agent at pressures between 1 and 10 MPa and temperatures between 1300 and 1600 ° C generates a H ₂ - and CO-rich raw gas being, being - one in a raw fuel silo ( 2 ) stored raw fuel of a facility ( 3 ) is added to the fuel for drying and grinding, - the fuel dust is then added to the filter ( 4 ) is freed from entrained drying and recirculating gas, - in a combined dust-collecting and metering vessel ( 5 ) set the fuel dust under operating pressure and in the fluidized state in the defined stream in a dust delivery line ( 6 ) is introduced, - the fuel dust in the fluidized state by means of flow promotion through the dust delivery line ( 14 ) the entrainment gasification reactor ( 7 ), - several combined dust-collecting and metering vessels ( 5 ), which are discontinuously (cyclically) filled with combustible dust and pressurized their contents to the entrained flow gasification reactor ( 7 ) continuously, after the filling and Bespannungsvorgang the setpoint for the fuel mass flow control on the control valves ( 11 ) of the dust conveyor lines ( 6 ) of the first and second dust transfer and metering vessel ( 5 ), whereby a share divisor ( 18 ) a displacement of the setpoint from the first to the second control valve ( 11 ) and the displacement of the setpoint takes place via a ramp whose time t1 is adjustable and the output of the ramp with the mass flow setpoint for the second control valve ( 11 ) and for the first control valve the output of the ramp is subtracted from 1 and multiplied by the mass flow setpoint, whereby parallel to the control of the control valves ( 11 ) the supply of fluidizing gas ( 16 ) under the fluidized beds ( 15 ) is started and the support is received. System according to claim 1, characterized in that the fuel dust of the common dust delivery line ( 14 ) by means of a dust flow divider ( 19 ) on several delivery lines ( 14a . 14b . 14c ) is divisible. System according to claim 2, characterized in that it is dimensioned such that the ratio of the cross section of the split conveyor lines ( 14a . 14b and 14c ) to the support line ( 14 ) is 1.5 to 3 times. System according to one of claims 2 to 3, characterized in that for the uniform application of the fuel dust of the plurality of split dust conveyor lines ( 14a . 14b . 14c ) after the dust flow divider ( 19 ) for a pipeline a quantity measurement ( 9a . 9b . 9c ) and a controlled according to the quantity measurement control valve ( 20a . 20b . 20c ) are arranged. System according to one of claims 2 to 4, characterized in that for the uniform application of the fuel dust of the plurality of split dust conveyor lines ( 14a . 14b . 14c ) after the dust flow divider ( 19 ) for each delivery line a quantity measurement ( 9a . 9b . 9c ) and a respective controlled in accordance with this quantity measurement control valve ( 20a . 20b . 20c ) are arranged. System according to one of the preceding claims, characterized in that the from a Staubschleusungs- and Dosiergefäß ( 5 ) mass flow of fuel dust in accordance with the setting of this dust lock and dosing ( 5 ) associated control valve ( 11 ) in the associated delivery line ( 6 ) is controllable. System according to one of the preceding claims, characterized in that of a Staubschleusungs- and Dosiergefäß 5 discharged mass flow of combustible dust in accordance with the above this dust-collecting and metering vessel ( 5 ) associated control valve in the fluidizing gas line ( 17 ) set amount of fluidizing gas is adjustable. System according to one of the preceding claims, characterized in that it is dimensioned such that the pressure loss in the dust conveyor lines ( 14 . 14a . 14b . 14c ) a maximum of 20% of the pressure in the dosing vessel ( 5 ) is. System according to one of the preceding claims, characterized in that in the common dust delivery line ( 14 ) a quantity measurement and controller for the total dust flow ( 21 ) are arranged and in accordance with the in this quantity measurement and controller for the entire dust flow ( 21 ) determined mass flow the the dust lock and Dosiergefäßen ( 5 ) total inflowing amount of fluidizing gas via a control valve for the total amount of fluidizing gas ( 22 ) in the fluidized gas line ( 16 ) is controllable. System according to one of the preceding claims, characterized in that the fluidizing gas is given by an inert gas. System according to one of the preceding claims, characterized in that an infeed of auxiliary gas ( 13 ) in a dust delivery line ( 14 . 14a . 14b . 14c ) given is. System according to one of the preceding claims, characterized in that the diameter of a dust delivery line ( 14 . 14a . 14b . 14c ) Can be enlarged over the conveying length, wherein the flow rate can be reduced by half by the extension of the dust delivery line.

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